In the early days of radio, producers, directors and scriptwriters were well aware of the listening public's fascination with subject matter tinged with wrongdoing. Stories of right and wrong, crime and punishment, and law and order kept audiences of every age hooked for more than thirty years.

This work covers 300+ syndicated radio mystery and adventure serials that aired in the early or middle twentieth century. To be included, a series must have had one or more regularly appearing characters who fought against espionage, theft, murder and other crimes. Each entry includes series name, air dates, sponsor, extant episodes, cast information and synopsis.